Update from Judith93585
Posted , 9 users are following.
I just returned from my optometrist for a refraction of both eyes. I have been given a prescription for eyeglasses at-1.25 sphere and small cylinder for each eye. My optometrist is surprised I can read phone and computer screen distances as well as I do.
I expressed my concern about seeing much better with my RE than LE in real life and my interest in a lens exchange to bring both eyes to the same power. He would not recommend a lens exchange even with a small difference. He has a great deal of experience with cataract patients and believes I may get used to my new vision in time. I have a new prescription for glasses and will proceed with purchasing new lenses for my Silhouette frames which seem to last forever. He recommends simple distance lenses rather than progressives which I can wear or not as I please. He recommends I simply remove my glasses for reading phone and computer screen but will add something to the lenses for reading if it becomes necessary.
Many thanks for all your attention and support!
To be continued ...
2 likes, 38 replies
judith93585
Posted
Thanks Ron. Sounds like CR-39 would be best if available for a particular need followed by Trivex... Do you think CR-39 is also made by Zeiss and others or only Hoya?
RonAKA judith93585
Posted
The down side of CR-39 is that it is apparently brittle and there can be issues with frames that require holes to be drilled in the lens. So, if that it the type of lens you plan on, then it may not be the best choice. CR-39 dates back to the 1940 where it was originally used in making military plane fuel tanks. I suspect it is a generically available material and may different manufacturers can use it if they choose to.
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The closest alternative is Trivex. It has higher tensile strength and resistance to cracking so it suitable for frames that require holes drilled in the lens itself. It is UV resistant and does not require UV coatings and is more scratch resistant. At 45 it does not have as high an Abbe value as CR-39 but it is higher than all the higher index lenses, and should be fine for optical quality. I believe it is available to all lens makers (Hoya, Essilor, Zeiss) if they choose to use it. You would have to ask your optical supplier if they can get it. It is likely to be a higher cost than the CR-39. Trivex is much newer from about 2001, and was developed as a bullet proof "glass" for the military. It is definitely a different material than the much older CR-39.
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The material you want to avoid is the generic "polycarbonate". It is the poorest choice of all, but may be the least expensive. It scratches easily, is not the strongest, and has the very lowest Abbe value. It was developed for NASA space helmets.
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Cost no concern, I would pick Trivex if you can get it.
judith93585
Posted
Thanks Ron. I'll be checking with optical shops today.
Lynda111 judith93585
Edited
I think I have mentioned I use Systane Hydration PF (preservative-free) eye drops in the multi dose bottle.
BTW, my prescription readers and distance eyeglasses are made from CR-39.
Years ago before I had cataracts was quite near-sighted , all my eyeglasses were made from CR-39.
Never had any issues
judith93585
Edited
Thanks Lynda, I like Systane Hydration PF too. I also use Refresh Relieva PF for a change of pace.
I went shopping for glasses at the optical shop that takes my insurance. What a difference in price! Lenses alone are 25% of the cost of the affiliated optical shop with more and better add ons. Frame is half price.
Off topic - I just came in from walking my small elderly dog. A man in the neighborhood was walking his German Shepherd and another dog. The German Shepherd even on leash was able to charge my dog and the owner could not pull him off. The barking and struggling seemed to last forever. Even while being dragged away the German Shepherd kept lunging and barking. Miraculously, my dog is unhurt.